Oliver isn't bad. I personally prefer Olivier, but that might be a bit pretentious of me. ;) Annie is nice, but more as a nn for Anne, Annette, etc. Oliver and Annie as a sibset is going a bit strong on the orphan theme in my thinking.
I feel silly for not realizing the "orphan theme!" Now I'm definitely off the sibset :-)
"My idea of good company ... is the company of clever, well-informed people who have a great deal of conversation; that is what I call good company." ~JaneAusten